Add blessed entry points to isomorphic and dom

[zpao]

This adds the following entry points to the npm module

• react/dom (exposes client and server)
• react/dom/client
• react/dom/server
• react/isomorphic

cc @sebmarkbage

[sophiebits]

Do you often want both client and server? I'm ignorantly leaning towards not having react/dom.

[sebmarkbage]

Yea. I think my original naive idea was for react/dom or react-dom to be the client version only while the server would be react/dom/server or react-dom/server or something.

[zpao]

So drop react/dom directly? I think I'd prefer that over having one be a shortcut.

[sebmarkbage]

sure

[sophiebits]

bikeshed: is react/dom/browser nicer? "client" sounds weird to me in this context, dunno why.

[zpao]

isomorphic is pretty weird too :P

[zpao]

Updated. Left as server & client.

[sophiebits]

Not a fan of "browser"? I also might like "core" over "isomorphic" if we think that's an accurate descriptor.

[sebmarkbage]

"browser" is too ambiguous. canvas, webgl, three.js, art, a theoretical react-native for web etc... They're all browser.

[zpao]

closing in favor of #4097